The present exemplary embodiment relates to document processing systems such as printer, copier, multifunction devices, etc., and operating methods to transfer an image from an intermediate surface to a media substrate.
Traditional Intermediate Belt Transfer (IBT) systems using semiconductive back-up rolls (BUR) and biased image transfer rolls (ITRs) at a second transfer require constant BUR or ITR voltage control. The voltage is determined by a feed-forward control algorithm with a complex look-up table that depends on paper weight, paper size, temp, humidity, and simplex vs duplex in order to control the transfer field and maintain adequate transfer latitude. This system requires an enormous amount of sensitivity testing, algorithm development and confirmation testing. Experiments show that even mature, carefully constructed constant voltage control algorithms often set voltages far enough from the optimal voltage to significantly degrade image quality.
Disclosed is a transfer nip design that enables a simpler, more accurate/robust control algorithm. The second transfer nip is modified to enable a constant current control system similar to that employed at first transfer.
Incorporation by Reference
The following patents and patent application publications are totally incorporated herein by reference:
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U.S. Pat. No. 6,611,665 to DiRubio, entitled “Method and Apparatus Using a Biased Transfer Roll as a Dynamic Electrostatic Voltmeter for System Diagnostics and Closed Loop Process Controls,” issued Aug. 26, 2003.
U.S. Pat. No. 6,606,477 to Thompson et al., entitled “Method to Control Pre- and Post-Nip Fields for Transfer,” issued Aug. 12, 2003
U.S. Pat. No. 6,600,895 to Fletcher et al., entitled “Printing Machine and Method Using a Bias Transfer Roller Including at Least One Temperature-Maintaining Device,” issued Jul. 29, 2003.
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U.S. Pat. No. 5,164,779 to Araya et al., entitled “Image Forming Apparatus with Dual Voltage Supplies for Selectively Charging and Discharging an Image Bearing Member,” issued Nov. 17, 1992.
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Brief Description
In one embodiment of this disclosure, described is a method of marking an image on a media substrate using an intermediate image transfer printing apparatus, the intermediate image transfer printing apparatus including a photoreceptor surface; an exposure station operatively associated with the photoreceptor surface; a developer system operatively associated with the photoreceptor surface; an intermediate image transfer surface operatively associated with the photoreceptor surface; and an image transfer nip operatively associated with the intermediate image transfer surface, the image transfer nip including a Backup Roll and a Paper Escort Apparatus to engage a media sheet, and one or more of the Backup Roll, Paper Escort Apparatus and the image transfer surface including a dielectric material, the method comprising a) forming an electrostatic image on the photoreceptor surface representative of an image to be marked on a media substrate using the exposure system; b) developing the electrostatic image on the photoreceptor surface with toner material using the developer system to generate a developed image; c) transferring the developed image from the photoreceptor surface to the intermediate image transfer surface; d) advancing the developed image on the intermediate image transfer surface to the image transfer nip; and e) generating an electric field across the image transfer nip utilizing a constant current source operatively connected to the Backup Roll and the Paper Escort Apparatus, whereby, the generated electric field transfers the developed image from the intermediate image transfer surface to a media sheet.
In another embodiment of this disclosure, described is an intermediate image transfer marking apparatus comprising a photoreceptor surface; an exposure station operatively associated with the photoreceptor surface; a developer system operatively associated with the photoreceptor surface; an intermediate image transfer surface operatively associated with the photoreceptor surface; an image transfer nip operatively associated with the intermediate image transfer surface, the image transfer nip including a Backup Roll and a Paper Escort Apparatus configured to engage a media sheet, and one or more of the Backup Roll, Paper Escort Apparatus and intermediate image transfer surface including a dielectric material; and a controller operatively associated with the photoreceptor surface, the exposure station, the developer system, the intermediate image transfer surface and the image transfer nip, the controller configured to execute a process of marking an image on a media substrate using the intermediate image transfer marking apparatus, the process comprising a) forming an electrostatic image on the photoreceptor surface representative of an image to be marked on a media substrate using the exposure system; b) developing the electrostatic image on the photoreceptor surface with toner material using the developer system to generate a developed image; c) transferring the developed image from the photoreceptor surface to the intermediate image transfer surface; d) advancing the developed image on the intermediate image transfer surface to the image transfer nip; and e) generating an electric field across the image transfer nip utilizing a constant current source operatively connected to the Backup Roll and the Paper Escort Apparatus.
In still another embodiment of this disclosure, described is an intermediate image transfer marking apparatus comprising a photoreceptor drum; an exposure station operatively associated with the photoreceptor drum; a developer system operatively associated with the photoreceptor drum; an intermediate image transfer surface operatively associated with the photoreceptor drum; an image transfer nip operatively associated with the intermediate image transfer surface, the image transfer nip including a Backup Roll and a Paper Escort Apparatus configured to engage a media sheet, and one or more of the Backup Roll, Paper Escort Apparatus and intermediate image transfer surface including a dielectric material; a fuser; and a controller operatively associated with the photoreceptor drum, the developer system, the intermediate image transfer surface and the image transfer nip, the controller configured to execute a process of marking an image on a media substrate using the intermediate image transfer image marking apparatus, the process comprising a) forming an electrostatic image on the photoreceptor drum representative of an image to be marked on a media substrate using the exposure system; b) developing the electrostatic image on the photoreceptor drum to generate a developed image using the developer system; c) transferring the developed image from the photoreceptor drum to the intermediate image transfer surface; d) advancing the developed image on the intermediate image transfer surface to the image transfer nip; e) generating an electric field across the image transfer nip utilizing a constant current source operatively connected to the Backup Roll, the Paper Escort Apparatus and the dielectric material, whereby the generated electric field transfers the developed image from the intermediate image transfer surface to a media sheet; and f) fusing the image transferred to the media sheet using the fuser.